
Haladir |

Hey folks! Is there anyway to make a lost caster level do to prestige classes? I've looked, but don't really have time to deep dive for it. The joys of life and All that. Thanks!
There are a couple of ways to do it...
If you simply want to bump your character's caster level, you can take the Trait Magical Knack. (This trait is from the Advanced Players' Guide.)
This Trait does not change your character's spell per day, but it does increase your caster level by 2. It cannot raise your caster level above your character level. So, for example, if you are a Fighter 1/ Wizard 5/ Eldritch Knight 1 with the Magical Knack trait, you would prepare spells as a 5th-level wizard, and your Caster Level would be 7.
If you want to increase your spells per day, you would need two feats from the Player Companion Paths of the Righteous:
Favored Prestige Class, which allows you to select a prestige class as a favored class for the skill/hp boonus-per-level (and also give you a skill check bonus).
That feat is a prerequisite for Prestigious Spellcaster, which does actually increase your effective level as a spellcaster by 1.
So, for example, if you are the above Fighter 1/ Wizard 5/ Eldritch Knight 1, and you had the feats Favored Prestive Class and Prestigious Spellcaster, you would prepare and cast spells as a 6th-level wizard.

OmniMage |
If you are willing to use something from DND 3.5, there is the Practiced Spellcaster feat. Its from Complete Arcane. It increases your caster level in a single class by 4. It can't raise your caster level beyond your HD. It does not give more spell slots or spells known. Its useful for those who multiclass.
https://dndtools.net/feats/complete-arcane--55/practiced-spellcaster--2231/